1. Technical Field
The inventive concepts described herein relate to image processing, and more particularly, relate to an image processing method capable of providing an image with improved image quality by using two images obtained by capturing the same object under different light conditions and an image processing device using the above image processing method.
2. Discussion of Related Art
A digital camera includes an image sensor to generate an electronic image. Common image sensors may include a Charge Coupled Device (CCD) image sensor, a CMOS Image Sensor (CIS), and so on. An image sensor includes pixels arranged in a two-dimension array. Each pixel included in the image sensor is formed of a red, green or blue filter.
The image sensor receives light during particular time to obtain an appropriate image signal. The time for receiving the light is referred to as exposure time. To obtain an image having appropriate brightness and high signal-to-noise ratio (SNR), the exposure time is adjusted based on brightness of environment where an image is captured. The digital camera has such an automatic exposure adjustment function for automatically adjusting the exposure time according to brightness of the environment where an image is captured.
A problem arises when an image is captured in an environment where the light is insufficient. An image captured in such environment where the light is insufficient does not represent the object appropriately. In general, to solve such a problem, a flash emitting artificial light is used. It is possible to capture an image with sufficient brightness by emitting the light around the object through the flash. When the flash is used, the image sensor receives sufficient light during short exposure time. In this case, since the SNR becomes higher, an image with fine expression is captured.
However, undesirable effects arise when the flash is used. For example, such undesirable effects may include a red-eye effect, breaking of color balance, and so on. Furthermore, an object near the flash is excessively exposed by the light, while an object distant from the flash is scarcely exposed by the light. That is, since a background of the image captured using the flash is dark and a foreground thereof is bright, the brightness of the image is unnatural. In particular, an LED flash embedded in a portable communication terminal has a low output power and emits the light irregularly. For this reason, use of the LED flash causes a decline in the quality of image.